The invention relates to a collapsible-boxes gluing machine for producing collapsible boxes from blanks, with a folding station wherein the blanks provided with an adhesive strip are folded, a subsequently arranged transfer station, which has at least one conveyor belt pair consisting of a lower belt and an upper belt, and a collecting and compression device, wherein the flat-lying folded collapsible boxes are pressed for the bonding of the adhesive,
As known, collapsible-boxes gluing machines for producing collapsible boxes from blanks have several processing stations, which are successively traversed by the blanks/boxes.:
First the blanks are picked up one after the other from a stack in a high-speed feeder and fed individually directly to a folding station or at first to a so-called preliminary crusher, which precedes the folding station. In the folding station the blank parts provided with a glue strip are turned over by 180xc2x0, i.e. folded, for the purpose of producing an adhesive connection. In the preliminary crusher the folding flaps are folded back and forth prior to the application of the adhesive, so that the corresponding longitudinal groove lines are softened and made more pliant.
The folding station is normally followed by a so-called transfer station, where the boxes can be counted, marked andxe2x80x94if defectivexe2x80x94thrown out. Then follows a collection and compression device, wherein at first a scaled stream of folded blanks is formed, which subsequently is kept under pressure for a while between compression belts, so that the two blank parts are connected at the gluing seam. The final stage is usually a packaging device, where the flat, folded collapsible boxes are packaged in cartons.
The transfer station has the primary task of feeding the blanks provided with an adhesive which has not yet bonded to the collecting and compression device with all their parts correctly positioned. Between the compression belts of the collecting and compression device, the box parts to be bonded are fixed one on top of the other, in the shape they are conveyed. This leads to the fact that the relative position of two box parts with respect to each other can there no longer be corrected.
As known, the folded blanks are transported through the stations by means of two conveyor belt pairs, arranged at a distance from each other, so that they guide the blanks holding them from above and below on their sides. In boxes where on each longitudinal side a side flap, which is pressed down respectively by a lateral belt has to be overturned, in the folding station the undesirable so-called xe2x80x9cfish-tail effectxe2x80x9d can occur: By fish-tail effect one understands a relative displacement of the upper box parts, of the overturned side flaps to the lower box parts of the bottom, to the extent that the side flaps are slightly turned inwards in the front, i.e. their longitudinal edge is no longer precisely parallel to the longitudinal edges of the bottom. This undesired displacement is caused by the fact that the folding belt lifts the side flaps to be overturned in front, in the running direction.
It is the object of the invention to improve a generic collapsible-boxes gluing machine so that the folded blanks are transferred to the compression belts of the collecting and compression device with precisely positioned side flaps. This object is achieved with the features of claim 1.
According to the invention, in the transfer station the speed of the upper conveyor belt can be increased in relation to the speed of the lower conveyor belt, in order to displace the upper box parts in relation to the lower box parts, for the purpose of correcting the fish-tail effect.
The dependent claims contain preferred, particularly advantageous embodiments of the invention.